remove incorrect assert regarding 128-bit integers
remove incorrect assert regarding 128-bit integers

LLVM incorrectly reports 8 as the alignment of i128 on x86_64 but it
correctly reports 16 as the alignment of i128 on aarch64.

closes #3101

zig-lang/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,andrewrk/zig,zig-lang/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig